You cannot perform troubleshooting on an ad hoc basis in serious production
environments; to effectively solve a problem, you must follow a specific
methodology. This chapter presents three main approaches to troubleshooting and
describes how to select a suitable troubleshooting approach for the problem at
hand. As a troubleshooter, you must take your knowledge and aptitude into
account and take the approach you feel is most suitable. With a method to
follow, you can solve the problem more quickly and cost effectively than if you
approached the problem haphazardly. After you have chosen an approach, do not
switch to another one in the midst of the troubleshooting effort. Switching
methods often causes confusion, wastes time and effort, and impedes the
resolution efforts.

"Do I Know This Already?" Quiz

The purpose of the "Do I Know This Already?" quiz is to help you
decide if you really need to read this entire chapter. If you already
intend to read the entire chapter, you do not need to answer these questions
now.

The 10-question quiz, derived from the major sections in the "Foundation
Topics" portion of the chapter, helps you determine how to spend your
limited study time.

Table 6-1 outlines the major topics discussed in this chapter and the
"Do I Know This Already?" quiz questions that correspond to those
topics.

The goal of self-assessment is to gauge your mastery of the topics in this
chapter. If you do not know the answer to a question or are only partially sure
of the answer, you should mark this question wrong for purposes of the
self-assessment. Giving yourself credit for an answer you correctly guess skews
your self-assessment results and might provide you with a false sense of
security.

Which of the following is an example of a problem that would take place
at the network level of the bottom-up approach to troubleshooting?

An interface malfunctions.

A routing loop occurs.

A router heat sink needs to be replaced.

The duplex setting of a port is incorrectly set.

If you have exhausted the possibility of the problem occurring in all but
the final level of the top-down troubleshooting approach, which layer are you
concerned with?

Physical

Data link

Transport

Application

Using a divide-and-conquer approach, which layer would you begin with if
you isolated the problem to an access list on a router?

Physical

Data link

Network

Transport

The power of the Cisco IOS command set encourages which troubleshooting
approach?

Bottom-up

Top-down

Divide-and-conquer

Weighted fair

During the course of a troubleshooting case, you started checking the
physical devices first. Which approach have you taken?

Bottom-up

Top-down

Divide-and-conquer

LLQ (Low Latency)

A user has initiated a trouble call, and it seems like a trivial case.
Which approach should you most likely take?

Bottom-up

Top-down

Divide-and-conquer

Priority approach

Which one of the following is a problem that would occur at the first
level of the top-down troubleshooting approach?

The PortFast setting on a port is incorrectly set to off.

The STP state on an interface is incorrectly set to forward.

A jabbering port is identified.

An FTP client application is found to be corrupt.

Which of the following provides the guidelines for selecting the best
troubleshooting approach?

Apply experience, analyze the symptoms, and solve the problem.

Select a troubleshooting approach and determine the scope of the
problem.

Determine the scope of the problem, analyze it using your experience, and
solve it.

Determine the scope of the problem, apply experience, and analyze the
symptoms.

Using the divide-and-conquer troubleshooting approach, you decide to
begin troubleshooting a TCP/IP problem at the network layer. You determine that
the network layer is working properly. Based on this knowledge, which of the
following layers is/are not assumed to be working properly?

Physical layer

Data link layer

Transport layer

Application layer

Which troubleshooting approach is most appropriate to implement if the
problem is located at the network interface?

Bottom-up

Top-down

Divide-and-conquer

Class-based weighted

You can find the answers to the "Do I Know This Already?" quiz in
Appendix A, "Answers to the 'Do I Know This Already?' Quizzes and
'Q&A' Sections." The suggested choices for your next step are
as follows:

8 or less overall scoreRead the entire chapter. This
includes the "Foundation Topics" and "Foundation Summary"
sections, as well as the "Q&A" section.

9 or 10 overall scoreIf you want more review on these
topics, skip to the "Foundation Summary" section and then go to the
"Q&A" section. Otherwise, move to the next chapter.